/ Barcelona's Merce Festival is 4 days of street entertainment, including the Catalan Castell competition. This acrobatic test of human strength and balance builds human towers nine levels high! Catalonia is a proud district of Spain with a special indigenous culture unique in the world, and the towers are one fine example of their sense of fun and competition, and an expression of their independence. Hundreds of people are involved, and thousands standing in the plaza enjoy the spectacle. The tallest and most complex tower wins. Watch out below when they come crashing down.